pratt



A. D. PRATT.

SUPERHEATER BOILER;

APPLICATION FILED MAY 14, 1921.

Beissued Oct. 18, 1921.

A. D. PRATT.

SUPERHEATER BOILER.

APPLICATION FILED MAY 14, 1921.

Reissued Oct. 18, 1921.

A. D. PRATT.

SUPERHEATER BOILER.

I APPLICATION FILED MAY14,19ZI- v Relssued Oct. 18, 1921. 15,210.

6 SHEETSSHEET 3.

%- r ATTORNEYS A. D. PRATT.

SUPERHEATER BOILER.

1 APPLICATION FILED MAY14, I921. Relssued Oct. 18, 1921.

ATTORNEYS A. 0. PRAT T. SUPERHEATER BOILER.

APPLICATION FILED MAY 14, 1921.

Reissued Oct. 18, 1921.

VII/l 4/ f lm l E ATTORNEYS A. D. PRATT.

SUPERHEATER BOILER.

APPLICATION FILED MAY 14, 1921.

Reissued Oct. 18, 1921. 1 5,2 1 O.

6 SHEETS-SHEET 6.

V QU UUUUUW I N VEN TOR,

7 6J6 if ATTORNEYS jam-ran sures PATENT" OFFICE;

arm n. rnar'r orsiron'rm'ms, mnsnx assmnoa"rournnisncodk a; wmcox consmr, or nsxom,"nnw unsay,m CORPORATION ormaw .rnasmr I I i i slicci flcation otkeiu'ued was; 10.13%), ma

citizenv of the United States, residing" at- Short Hills, in the] couuty of Essex and State of New Jersey,'l1ave invented certain new and useful Improvements in Superheater-Boilers, of which the following is a I specification.

My invention relatesto steam'superheaters and. will be understood by reference to the accompanying drawings in whiche- Flgure 1 is a vertical longitudinal section through a boiler embodying oneform of the invention; Fig. 2 an enlarged detail vertical section taken parallel with the boiler. tubes showing the relative location of the superheater tubes thereto; Fig. 3 a partial lan view and partial horizontal section, the atter being on the plane of the line 3-3 of Fig.1; Fig. 4 atransverse section onth'e plane of the line 4-4, of Fi 1; Fig. '5' a partial plan view and partial orizontal section of a' boiler set in a plant with additional boilers offthe same type toillustrate the in space between the boilers by the use 0 curved superheater tubes; 6, 7, 8'; ,9 detailed views showing liferent metheds' of supporting the headers or manifolds of the superheater in the side walls of the'boiler; Fig. 10 a partial plan view of the lowermost superheater header; Figs. 11, 12,

13, 14 and 15' detailed views of one of the superheater headers, partly in section, to illustrate methods of-connecting the tubes with the headers; Fig. '16 a partial detail section takenparallel with the boiler tubes to"""illustrate a construction in which the superheater tubes rest upon boiler tubes;

and Figs. 17, 18, 19 and 20 diagrammatic views to illustrate various arrangements of the secondary superheater.

Similar reference numerals indicate simi In'the drawings I have-shown my invention as a plied to a standard'form of Babcock & 1lcox-cross-d-n1m; oiler in which the numerahl-l designates thefront, and 2 the rear ofvthe;-'setting. Within the setting is a bank of generating'tubes ,3 inclined u ward fromfl=-the frontto the rear. over t e comhustionchamber 4. ;-The boilerisshown 'as-rfired with V as chain ;-.gra te stoker- 5 over which :is the usual ignition arch '6, and a.v

grose walli, .The' generating tubesare e;-

scribed, with a short transverse ba eg 'l nu ber as, isle-semi 10. 54,103, filed October. a, 1915. Application for reissue fled mu, .1921. beds] Io. 488,568.

panded into front and rear heade and- 5 5 9 r est r y- The heat h a ers re will n e i plpes 1 w ef ess'rd 'i 1 a and the rear headers are connected to said" druin byjw'ater,andsteaincirculatorsand r 13 respectively. A" short roof ,,l, jafl{e I14 axe-o supported upon the cross-wall 7 and fthe 7: lower end of the lowermost row of tubes',f@ and upon said roof baflie' is supportedj cross-wall lfi'extending upward, in the par? ticular boiler selected forillustra'tion, 'tlieilli li height of six rows of tubes. A longitudinal baffle' 16 extends fromtherear portion of"? cross-wall 15 and is supported upon s eer the rows of tubes. A vertical bafile'f lf rises; J from the rear portion of bafiie lfito the u '10 permost row of tubes. Theibafili e and its upward extension 18'', causes it gases to flow along thetubes .belowfjthe -baflfl 16 and to cross the bank atthe u'ptakejend 5 of the tubes, and thence flow downward and" upward as indicated by the arrows, to jphefi uptake 19. Located in the triangularispacef below the horizontal circulating ipes and jj above the inclined tu es, is a stan ard formic of U-tube superheater 20 to which I shall"? refer as the rimary superheater. .The head ers or mani olds 21 and 22, of the primary s'uperheater, are built into, ,or sup rte'd'} upon, the brickwork above bafile 18,: ringing the hand-holefittings above the third" pass of the boiler where they are exposed only to moderate temperatures. Steam'from' '1 drum 11 flows through the main 23 into the I intake header 21, passes through the super- "'90 heater tubes and is taken from the outlet header 22. The parts so far'desc'ribed are of standard form and design.

In order to meet present day requirementsfor superheated steam I have designed a new form of superheaterand have located it within the bank of generating tubes where it f will be subjected to a relatively high degree of heat. Thenew form of su rheater may comprise one or more sets of tubes receiving steam directly from the boiler drum, or if a .rangements I have illustrated diagrammaticall in Figs. 17 to 20. v .In the form and arrangement illustrated in Figs. 1 to 4 (shown diagrammaticallyin Fig. 17) the secondar superheater comprises two sections, an is connected to the standard superheater 20. .The latter, as before stated, will be referred to as the .pri-

mary superheater. One section of the secondary supe heater consists of a set of tubes.

, 24 and the other of a set of tubes 25, the

tubes of both sections being bent or bowed more or less either on tangents, or that their centerlines approach the arc of a circle. The tubes 24 are expandedinto headers 26 and 27, and the tubes 25 are expanded into headers 28 and 29. These headers are at the sides of the boiler-and are set parallel with the boiler tubes. The secondary superheater, when comprising one or more seetlons, may be placed in any position'in the boilerbetween the water-tubes. 'here a comparatively low degree of superheat is desired it will be laced more remotefrom the furnace than s own in thedrawings. For

a high degree of superheat I prefer to place the super eater substantially as shown in 1, that is, one section between the sec: on and th'rd rows of tubes, and the other between the third and fourth rows of'tubes from the bottom of the bank. The tubes of the superheater boiler tubes protecting the superheater from the direct radiant heat of the furnace- Owin to the smaller size 'of the superheater tu s, two rows can beput in place of a removed row of water tubes. In such location a relatively small amount of heating surface is passed over before the gases reachthe superheater-in the boiler shown, about 14%-whereas, with the superheater located in the triangular space above the tubes about '-.L5% of the heating surface is assed overbefore the gases reach the super eater.

3 the boiler tubes,

Under "the high temperature to which the.

tubes of the secondary superheaters are subjected the tubes are liable to spring or to become distorted, and one of the advantages of my improvement is that the amount of springing ordistortion in a vertical direction is limited by the boiler tubes 3 which are above and below the superheater tubes as shown in Fig. 2 A further advantage lies in'the fact thatathe bending of the superheater tubes enables them to expand and contract within their length by bowi more or less without pushing on the hea ers as. they would if the tubes were straight. In-

stead of the relation of the superheater tubes to the boiler tubes, as shown in Fi .2, the former may be made, to rest direcfiy upon as' shown in Fig. 16. \Vhen arranged as shown in Figs. 1 to 4,

and Fig. 17, the saturated steam passes-from. the'drum '11 through the inlet header 21 of the primary superheater,

twomains23 to the sections thus occupy the spaces which would ordinarily be occupiedv by boiler tubes, the two lowermost rows of -dispense with the primary superheater.

removable steel panel 37.

header 22, and thence through two connecting pipes to the two sections of the secondary superheater. 30 leads to the lower end of the. header 26 of the upper section of the secondary superheater, the steam flowin 24 to the header 2-7, and E the outlet connection 31, leading from the upper end of header 27. The other connec tion 32 from header 22, leads-to the lower end of the inlet header 28 of the other section of the secondary superheater, the steam flowin outlet eader 29, and thence through the'outlet connection 33 from the upper end of the header. As shown in Figs' 3 and 4 the headers are supported .inthe side walls of the setting so that there is a parallel flow tween all of the superheater tubes, and flows in opposite direction through the tubes of the two sections from one header to theother of the section: Instead of the arrangement above described, the secondary superheater may consistof a single set of tubes, as shown diagrammatically in Fig; 18, the steam flowi through the two superheaters as indicated y the arrows.

In some instances itmay be desirable to superheater, in be .led directly WhlCl'l case, the steam may from the drum 11 through main 23 to the lower end of the header 26, and thence throu h the tubes 24 to the outlet header'27, as in icated in Fig. 19. I have also indi- One of these connections through the tubes rom thence through cated in Fig. 19 partition walls 26' and 27' in the headers 26 and 27 to cause aback and forth flow of the steam through the superheater. In Fig. 20 I have shown another arrangement primary superheater and in which the two sections of the secondary superheater are connected in series by a pipe 34'. In this arrangement all of the steam flows from the boiler through the first section and then through the second section of the secondary In Figs. 6, 7, 8 and 9 I have shownseveral methods 'for .supp'ortin the super heater headers in the side .wa ls of the setting. Thus in Fig.6 'the headers are suspended by means of bolts 35 from I-beam 36 above the headers. This I-beam also supports the brickwork of the boiler side wall above the headers. Access to the hand-hole fittings and headers may be had through a In Fig. 7 the headers are shown as supported directly upon the brickwork 38. A bearing piece 39 formed of an angle iron is embedded in the brickwork. Fig. 8 illustrates'another construction in which the headers are supported upon an Lbeam tO below the lower headers.

which omits. the standard or The brickwork 4L'above the headers is supported upon I-beam 'The flanged fitting 31, for discharging the steam from the upper header 27 is also shown. The inclined connection 32,- shown in dotted lines, is the inlet to the header 28 of the lower secondary the outlet connection 33.are soarranged that the *will not interfere with the removal rep aci'ng of the superheater tubes.

In Fig. 11 I have shown a detail of one of the superheater headers, partly in section, with'the curved tubes on one side and hand-hole fittings 46 on the other side through whichthe tubesmay be inserted or withdrawn. The steam inlet connection 30 is shown as riveted to the side of the header near its .end, the head being circular at that point. An end view'of one of the headers, partly in section is shown in Fig. 12. The

method of rolling the: superheater tubes in the headers, if of the form'shown in Fig. 11, is shown in Fig. 13. It will be noticed that the thickness of the header is such as to give a suflicient length of seat for the tube in a plane perpendicular to the axis' of the tube In Figs. 14- and 15 is shown an arrangement of superheater headers with a ste ped m Figs. 14 and 15 the side of the header tube sheet 47 so that the ends enter the oles in the headers in .a normal or right angle direction. This allows the tubes to be expanded in the ordinary way. Asalso shown having "the hand-holes may be made thicker than the sidethrough which the tubes enter, or thicker than the other sides. This construction applies to a boiler header as well as to a superheater header, and is advantageous. in some constructions where high pressures are to be carried.

, An advantage of using tubes bent so that their center lines approach the arc of a circle is that they can be. withdrawn from the sides of the superheater in locations where there is a comparatively narrow passage between the boilers. .TlllS possibility is illustrated in Fig. 5 In a boiler for which. I designed the'present superheater the boiler furnace was about twenty-four feet wide, and the tubes about twenty-six feet long. If straight tubes had been used it would have been necessary, for the removal of the tubes, to make the passages between the boilers practically as wide as the length of the tubes This'would make any such super heater impracticable in the modern boiler room equipped with large size units. The superheater tubes',\beingon the are of a circle, can be withdrawn into a passage of sli htly less than ten .feet.

t Wlll be noted that the superheater tubes may be drawn out and replaced through the superheater headers, this being a highly desirable feature. It will-also be noted that the superheater tubes are exposed to the action of the hot gases throughout their entire length from face to face of the superheater boxes, while at the same time the tubes may be readily removed and replaced; alsothat the superheater headers or boxes or portions f f them form part of the superheating' surace.

A primary .superheateris preferably used In connection with this special superheater, though this may or may not be used,within the scope of the broader claims.

' .Various changes and modifications may b made'as suggested in the foregoingdescription, thus while I- have shown the secondary superheater, in Figs. 1 to 4, made up of two sections only, a single section may be used as shown in-Figs. 18 and 19. Also the arrangement of superheater tubes may vary, that is, instead I of four tubes per cluster, handled through a single hand-hole, there Also the tubes may be arranged ina single row or' any more than the two'rows shown in the drawings.

What I claim and desire to secure by Letters Patent of the United States, is

1. A water tube boiler havin longitudinal water tubes, a superheater l 'iaving transversely extending bent tubes between the Water tubes, and baflling for directing the products of combustion, said bafliing having a horizontally. extending baflle. above the lower water tubes to expose them to the flame and gases for the major portion of their length and an upwardly projectingv baflle extending therefrom transversely of the water. tubes above the superheater and arranged to give the gasesa restricted upward transverse pass across the water tubes located above the superheater.

2. A water: tube boiler having front and rear water'compartments connected by longitudinai -horizontally extending .water tubes,.a superheaterhaving transversely extending tubes between the water tubes with bent portions within the setting, and baflling for directing the products of combustion, said baflling having a baflle extending in a horizontal directionalong the lower rows of the water tubes located above the superheater to expose the water tubes below the superheater to the flame and gases for the major portion of their length, and an upwardly projecting bafile extending therefrom may be one, two or three or more than four.

transversely of the water tubes above the superheater and arranged to give the gases a restricted upward transverse pass across the water tubes located above the superheater.

3. A water tube boiler having front and rear headers connected by inclined water tubes, a primarysuperheater above the bank of water tubes, a secondar superheater exr tending transversely of ant between rows'of ,the tubes above the superheater than at the inlet water tubes and having bent portions within,

between the superheater,

the setting, pipe connections steam drum and the primary and between the latter and the secondary superheater, and bafiling for directing" the products of combustion, at least a part of this bafliing extending transversely. ofthe water tubes above the secondary andgivin' a restricted pass to the gases among sai upper water tubes. p

4. water tube boiler having water" compartments connected by longitudinal horizontally extending water tubes, a superheater having transversely extending-tubes between the rows of water tubes and proand bat-s vided with bent or curved portions,

fling for directing the products ofcombus tion,'said baflling having a horizontally ex-' tending portion among the water tubes over the superheater, and also having a portionextending upwardly and transversely of the water tubes above the superheater, said baffling forming an upward transverse ass for gases whlchis narrower among t e water to the water tubes below the superheater, the

superheater.

lowermost water tubes being exposed to the flame andv gases for the major"portion' of their length. 5. A water tube boiler having front and rear headers connected by inclined water tubes, :1 superheater comprisin boxes'located in the side walls, and havrn their inner portions exposed to t e gases, said boxes being connected by bent tubes extendino' between rows of water tubes, the

supereiieater tubes being removableand re placeable through the boxes.

6. A water tube boiler having water compartments connected by longitudinal horizontally extending water tubes, a superheater having transversely extending tubes at least between the rows of'water tubes and pro vided with bent or curved portions within the setting, and battling for directing the products of combustion, said bafiling having a horizontally extending portion among the water tubes over the su erheater, and also having a portion. exten in [upwardly and transversely of the water tn 5 above the superheater, said bafiiing forming an upward transverse pass for the gases'which is narrower among the water tubes above the su- Eerheater than at the inlet to the water tubes elow the jsuperheater' and to thesuperheate'r, and another bafile depending among the upper water tubes and'extending transversely of them arranged to give the gases another transverse down and up pass through said upper water tubes.

ARTHUH D. PRATT. 

